Printed circuit boards comprise a support structure formed from an electrically insulative material and having formed on at least one side thereof a series of electrically conductive paths or leads in the form of traces and pads. Typically, a plurality of apertures are formed through the board, and components are mounted on the board by insertion of electrically conductive pins extending from each component through the apertures. Solder connections are then formed between the conductive pins of the components and the conductive leads of the printed circuit board, thereby completing the necessary electrical connections between the various components.
During fabrication of the printed circuit board, defects occur, such as, for example, shorts between traces and pads as well as defects in the continuity of traces resulting in "open" faults. Various systems have been proposed for the repair of printed circuit boards, such as, for example, the system and method disclosed in U.S. Pat. No. 4,469,553 issued to Robert E. Whitehead on Sep. 4, 1984. The system of the '533 Patent projects circuit board data, such as, for example, "Gerber" data from a plasma screen of a computer onto a half mirror. A printed circuit board is positioned beneath the mirror. The board can be viewed through the mirror while at the same time the "Gerber" data is projected on the mirror in registry with the circuit board, so that an operator can view the circuit board through the mirror for correlating the "Gerber" data projected onto the mirror with the actual circuit board positioned below the mirror.
A need has arisen for a improved system for the analysis and repair of errors found in printed circuit board manufacture.